Studies of selective adsorption, desorption and reuse of chemically altered biomass produced from aquatic macrophytes for treatment of metal-containing wastewater

摘要

The aquatic macrophytes Salvinia sp. and Pistia stratiotes have a natural capacity to adsorb various elements, including heavy metals. This capacity was enhanced with a chemical treatment using NaOH alkaline solution for Salvinia sp. and a mixture of both Salvinia sp. and Pistia stratiotes at a proportion of 1: 1, whose respective biosorbents were called SSOH and MBOH. Adsorption tests were done in a ternary system containing the metals copper, lead and manganese; the parameters considered were: starting concentration, kinetics, pH and temperature. The adsorption isotherms for SSOH had a maximum adsorptive capacity of 50.20, 53.85 and 14.68 mg g(-1) for Cu, Pb and Mn, respectively; for MBOH, maximum values were 44.62, 35.17 and 15.74 mg g(-1) for Cu, Pb and Mn, respectively. The metals displayed different behaviors with pH variation. The results also showed an adsorption preference of Cu > Pb > Mn for SSOH. Desorption and readsorption studies were also carried out, showing 100% desorption and increased adsorption capacity in readsorption tests. Surface area and porosity analysis with the Brunauer-Emmett-Teller (BET) method indicate that after chemical modification, MBOH and SSOH biomasses had their surface increased in comparison to SS, with values of 165.5657 (MBOH), 157.4392 (SSOH) and 78.9432 m(2) g(-1) (SS).